1. Field of the Invention
The present invention relates to a gas combustion apparatus using gas fuel or a gas heating cooker to be applied to a grill to be engaged wth a gas range by the use of the gas combustion apparatus, or to a grill/oven as a box-type cooker.
2. Description of the Prior Art
Generally, the conventional gas combustion apparatus and the gas heating cooker of this type has two ranges 2 on the top face of the main body 1 and a grill 3 having a door in a gas range as shown in, for example, FIG. 12. Also, in addition, a grill/oven is put into practical use as a box-type cooker. As the system of the grill 3, as shown in (a) in FIG. 13, there is a single-face toasting grill which heats the top face of the cooked food 5 placed on the toasting net 6 by the upper burner 7 with the ceramic perforated plate, wire guaze or punched plate, engaged near the ceiling of the heating chamber 4, as a combustion plate, as shown in (b) in FIG. 14, a toasting net 6 for having the cooked food 5 thereon is provided at the upper, lower central portions of the heating chamber 4, an upper burner 7 which is similar to one of the single-face toasting system is engaged with the ceiling portion of the heating chamber 4, a lower burner which forms in the horizontal direction the Bunson-type flame is engaged on both the sides of the lower portion, with a both-face toasting grill being provided to simultaneously heat both the upper, lower faces of the cooked 5 by each of these burners.
A stock saucer 9 receives oil stock or the like falling from the cooked 5. It is filled with water 10 so that the fallen oil may not be evaporated and burned.
In the single-face toasting grill shown in FIG. 13, the cooked food 5 is heated on the top face with the radiation heat from the upper burner 7, is turned over after the lapse of the given time to heat the other face, with the result that a longer time is taken and the bother of turning over the cooked food is required.
In the double-face toasting grill shown in FIG. 14, both the upper and lower faces of the cooked food 5 are simultaneously heated respectively by the upper burner 7 and the lower burner 8. However, as the lower burner 8 is located on both sides of the lower portion of the heating chamber 4, the combustion of the respective right, left lower burners 8 can not reach the central portion and directs halfway in the upper direction. This is because the draft force of the combustion gas is stronger than the jetting force (which changes slightly depending upon the gas pressure) of the lower burner 8. The raised position becomes a heating position. Accordingly, a portion where the combustion gas directed in the upper direction hits the toasting net 6 becomes maximum at temperature, and the temperature of the central portion, the temperature of both the end portions becomes lower, and the temperature distribution of the toasting net 6 portion at the combustion of the lower burner 8 becomes as shown in FIG. 15. As a result, only double-face toasting grill of inferior temperature distribution is provided, extremely uneven toasting is caused on the lower face of the cooked food 5, thus resulting in inferior cooking.
Accordingly, although the toasting is of double-face the, it is necessary to turn over the cooked food 5 during the cooking operation or to replace the position in order to prevent uneven toasting, thus lowering the value of double-face toasting.
Also, so as to get the combustion gas to reach the central portion of the toasting net 6, the width L of the heating chamber 4 has to be made about 15 cm or lower, so that the amount of the food to be cooked to be toasted at one time becomes extremely small. As the interval between the lower burner 8 and the toasting net 6 is required to be made larger, with the result that the main body becomes larger in size and the thermal efficiency becomes inferior. The lower burner 8 cannot be arranged immediately under the cooked food 5, because the oil stock falls onto the high temperature portion of the lower burner 8 from the cooked food 5 so as to be ignited or cause a lot of oil smoke. Or it cannot be put into practical use, because it is difficult to put in an out the food so as to clean the case 4' of the heating chamber 4 considering the construction.
As shown in FIG. 16, the upper burner 7 and the lower burner 8 of FIG. 14 are composed of a pair of right, left burners. An ignition unit 7u of the ignition plug 7c, a firing burner 7d, a firing detector 7e is mounted on each of the upper, lower burners 7, 8 so that the construction becomes more complicated and higher at cost. The ignition unit 7u is engaged only with the single side of a pair of right, left burners of the upper, lower burners 7, 8. The pair of right, left burners may be simultaneously ignited with the length of the flame of the firing burner 7d, but the first is gone out if the ignition is confirmed. If the burners 7a and 8a are blown out on the side where the apparatus of the ignition detector 7e does not exist during the combustion, there is a risk of the raw gas being released without the flame transfer from the burners 7b and 8b on the engagement side of the ignition detector 7e. Reference character 7f is an exhaust port, reference characters 7g, 8g are gas supply pipes to the upper and lower burners.